UCL CENTRE FOR MATERIALS RESEARCH

Research Summary

My research interest is X-ray diffraction using synchrotron radiation (SR). During the Bell Labs years, I developed the methods for studying surface structure using X-ray diffraction. These methods, based on crystal truncation rods, have become the definitive technique for the determination of the atomic positions at surfaces and interfaces. These surface methods are still used today at the major SR facilities, NSLS (Brookhaven), ESRF (Grenoble), APS(Chicago) and SLS (Villigen).  I was awarded two prizes for the surface structure work, the Warren Prize in 2000 and the Surface Structure Prize in 2011.

To develop the methodology of X-ray diffraction with SR, I built two beamlines.  The first was a dedicated surfaces and interface structure beamline X16A at the National Synchrotron Light Source (Brookhaven).  The second was 34-ID for coherent diffraction at the Advanced Phoyon Source(Chicago).  More recently I have been developing methods of using the very high coherence of the latest SR sources to enable direct 3D imaging of structure. This is potentially useful for examining strain distributions inside complex materials on the nanometre length scale.

The coherent X-ray diffraction methods will develop and expand further at the Diamond Light Source (DLS) located at Rutherford Appleton Lab (RAL) near Oxford. I am a founding "Diamond Fellow" of the Research Complex at Harwell (RCaH), also located at RAL.  This is a meeting place of physical and live scientists interested in the transfer of methodologies from the physical to the life sciences.  Materials and biological imaging are the main directions under development there.

Three major grants are supporting the work of my group, which is now divided between the UCL and RCaH centres.  The first, entitled "nanosculpture", looks at strains induced in nanometre-sized crystals either synthesised from atoms in a 'bottom up' procedure, or else carved by lithography from bulk materials in a 'top down' approach.  The second is to study the structure of the human chromosome by X-ray imaging methods.  The third is to develop new X-ray imaging methods based on deliberate modulation of the phase by suitably developed X-ray optics.